Siemens SINAMICS G120X - Simplified Function Diagram of the U;F Control; U;F Control; V;F Control

Parameters
Number Name Factory setting
p0010 Drive commissioning parameter filter 1
p0230 Drive filter type, motor side 0
p0235 Number of motor reactors in series 1
p0350[M] Motor stator resistance, cold 0 Ω
p0352[M] Cable resistance 0 Ω
For additional information on parameters, please refer to the parameter list.
6.7.2 V/f control
6.7.2.1 U/f control
Overview
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In the "Flux Current Control (FCC)" U/f version, the converter controls the motor current (starting
current) at low speeds.
Figure 6-67 Simplified function diagram of the U/f control
The U/f control is a speed feedforward control with the following properties:
● The converter sets the output voltage on the basis of the U/f characteristic.
● The output frequency is essentially calculated from the speed setpoint and the number of
pole pairs of the motor.
● The slip compensation corrects the output frequency depending on the load and thus
increases the speed accuracy.
● The omission of a control loop means that the U/f control is stable in all cases.
● In applications with higher speed accuracy requirements, a load-dependent voltage boost
can be selected (flux current control, FCC)
For operation of the motor with U/f control, you must set at least the following subfunctions
appropriate for your application:
● V/f characteristic
● Voltage boost
Advanced commissioning
6.7 Motor control
SINAMICS G120X converter
Operating Instructions, 06/2019, FW V1.01, A5E44751209B AC 377